scholarly journals Nascent chain-monitored remodeling of the Sec machinery for salinity adaptation of marine bacteria

2015 ◽  
Vol 112 (40) ◽  
pp. E5513-E5522 ◽  
Author(s):  
Eiji Ishii ◽  
Shinobu Chiba ◽  
Narimasa Hashimoto ◽  
Seiji Kojima ◽  
Michio Homma ◽  
...  
Keyword(s):  
Marine Bacteria ◽  
Marine Bacterium ◽  
Life Cycles ◽  
Protein Export ◽  
Primary Role ◽  
Dependent Manner ◽  
Physiological Conditions ◽  
Low Salinity ◽  
Nascent Chain ◽  
Shine Dalgarno Sequence

SecDF interacts with the SecYEG translocon in bacteria and enhances protein export in a proton-motive-force-dependent manner.Vibrio alginolyticus, a marine-estuarine bacterium, contains two SecDF paralogs, V.SecDF1 and V.SecDF2. Here, we show that the export-enhancing function of V.SecDF1 requires Na+instead of H+, whereas V.SecDF2 is Na+-independent, presumably requiring H+. In accord with the cation-preference difference, V.SecDF2 was only expressed under limited Na+concentrations whereas V.SecDF1 was constitutive. However, it is not the decreased concentration of Na+per se that the bacterium senses to up-regulate the V.SecDF2 expression, because marked up-regulation of the V.SecDF2 synthesis was observed irrespective of Na+concentrations under certain genetic/physiological conditions: (i) when thesecDF1VAgene was deleted and (ii) whenever the Sec export machinery was inhibited. VemP (Vibrioexport monitoring polypeptide), a secretory polypeptide encoded by the upstream ORF ofsecDF2VA,plays the primary role in this regulation by undergoing regulated translational elongation arrest, which leads to unfolding of the Shine–Dalgarno sequence for translation ofsecDF2VA.Genetic analysis ofV. alginolyticusestablished that the VemP-mediated regulation of SecDF2 is essential for the survival of this marine bacterium in low-salinity environments. These results reveal that a class of marine bacteria exploits nascent-chain ribosome interactions to optimize their protein export pathways to propagate efficiently under different ionic environments that they face in their life cycles.

scholarly journals Partitioning Effects during Terminal Carbon and Electron Flow in Sediments of a Low-Salinity Meltwater Pond near Bratina Island, McMurdo Ice Shelf, Antarctica

1999 ◽  
Vol 65 (12) ◽  
pp. 5493-5499 ◽  
Author(s):  
Douglas O. Mountfort ◽  
Heinrich F. Kaspar ◽  
Malcolm Downes ◽  
Rodney A. Asher
Keyword(s):  
Sulfate Reduction ◽  
Methane Production ◽  
Electron Flow ◽  
Fold Increase ◽  
Cyanobacterial Mats ◽  
Ice Shelf ◽  
Physiological Conditions ◽  
Low Salinity ◽  
Methane Production Rate

ABSTRACT A study of anaerobic sediments below cyanobacterial mats of a low-salinity meltwater pond called Orange Pond on the McMurdo Ice Shelf at temperatures simulating those in the summer season (<5°C) revealed that both sulfate reduction and methane production were important terminal anaerobic processes. Addition of [2-14C]acetate to sediment samples resulted in the passage of label mainly to CO2. Acetate addition (0 to 27 mM) had little effect on methanogenesis (a 1.1-fold increase), and while the rate of acetate dissimilation was greater than the rate of methane production (6.4 nmol cm−3 h−1compared to 2.5 to 6 nmol cm−3 h−1), the portion of methane production attributed to acetate cleavage was <2%. Substantial increases in the methane production rate were observed with H2 (2.4-fold), and H2 uptake was totally accounted for by methane production under physiological conditions. Formate also stimulated methane production (twofold), presumably through H2 release mediated through hydrogen lyase. Addition of sulfate up to 50-fold the natural levels in the sediment (interstitial concentration, ∼0.3 mM) did not substantially inhibit methanogenesis, but the process was inhibited by 50-fold chloride (36 mM). No net rate of methane oxidation was observed when sediments were incubated anaerobically, and denitrification rates were substantially lower than rates for sulfate reduction and methanogenesis. The results indicate that carbon flow from acetate is coupled mainly to sulfate reduction and that methane is largely generated from H2 and CO2 where chloride, but not sulfate, has a modulating role. Rates of methanogenesis at in situ temperatures were four- to fivefold less than maximal rates found at 20°C.

The localized assembly of extracellular matrix integrin ligands requires cell-cell contact

2000 ◽  
Vol 113 (21) ◽  
pp. 3715-3723 ◽  
Author(s):  
M.D. Martin-Bermudo ◽  
N.H. Brown
Keyword(s):  
Extracellular Matrix ◽  
Drosophila Embryo ◽  
Cell Contact ◽  
Primary Role ◽  
Dependent Manner ◽  
Muscle Attachment ◽  
Matrix Assembly ◽  
Attachment Sites ◽  
Genetically Manipulated ◽  
Cell Cell

The assembly of an organism requires the interaction between different layers of cells, in many cases via an extracellular matrix. In the developing Drosophila larva, muscles attach in an integrin-dependent manner to the epidermis, via a specialized extracellular matrix called tendon matrix. Tiggrin, a tendon matrix integrin ligand, is primarily synthesized by cells distant to the muscle attachment sites, yet it accumulates specifically at these sites. Previous work has shown that the PS integrins are not required for tiggrin localization, suggesting that there is redundancy among tiggrin receptors. We have examined this by testing whether the PS2 integrin can recruit tiggrin to ectopic locations within the Drosophila embryo. We found that neither the wild type nor modified forms of the PS2 integrin, which have higher affinity for tiggrin, can recruit tiggrin to new cellular contexts. Next, we genetically manipulated the fate of the muscles and the epidermal muscle attachment cells, which demonstrated that muscles have the primary role in recruiting tiggrin to the tendon matrix and that cell-cell contact is necessary for this recruitment. Thus we propose that the inherent polarity of the muscle cells leads to a molecular specialization of their ends, and interactions between the ends produces an integrin-independent tiggrin receptor. Thus, interaction between cells generates an extracellular environment capable of nucleating extracellular matrix assembly.

scholarly journals Dual Agarolytic Pathways in a Marine Bacterium, Vibrio sp. Strain EJY3: Molecular and Enzymatic Verification

2020 ◽  
Vol 86 (6) ◽  
Author(s):  
Sora Yu ◽  
Eun Ju Yun ◽  
Dong Hyun Kim ◽  
So Young Park ◽  
Kyoung Heon Kim
Keyword(s):  
Marine Bacteria ◽  
Marine Bacterium ◽  
Extracellular Enzymes ◽  
Alternative Pathway ◽  
Recombinant Enzymes ◽  
Red Macroalgae ◽  
Macroalgal Biomass ◽  
Sugar Unit ◽  
Branching Point

ABSTRACT Vibrio sp. strain EJY3 is an agarolytic marine bacterium that catabolizes 3,6-anhydro-l-galactose (AHG), a monomeric sugar unit of agarose. While the AHG catabolic pathway in EJY3 has been discovered recently, the complete agarolytic system of EJY3 remains unclear. We have identified five enzymes, namely, the β-agarases VejGH50A, VejGH50B, VejGH50C, and VejGH50D and the α-neoagarooligosaccharide (NAOS) hydrolase VejGH117, involved in the agarolytic system of EJY3. Based on the characterization of recombinant enzymes and intracellular metabolite analysis, we found that EJY3 catabolizes agarose via two different agarolytic pathways. Among the four β-agarases of EJY3, VejGH50A, VejGH50B, and VejGH50C were found to be extracellular agarases, producing mainly neoagarotetraose (NeoDP4) and neoagarobiose. By detecting intracellular NeoDP4 in EJY3 grown on agarose, NeoDP4 was observed being taken up by cells. Intriguingly, intracellular NeoDP4 acted as a branching point for the two different downstream agarolytic pathways. First, via the well-known agarolytic pathway, NeoDP4 was depolymerized into monomeric sugars by the exo-type β-agarase VejGH50D and the α-NAOS hydrolase VejGH117. Second, via the newly found alternative agarolytic pathway, NeoDP4 was depolymerized into AHG and agarotriose (AgaDP3) by VejGH117, and AgaDP3 then was completely depolymerized into monomeric sugars by sequential reactions of the agarolytic β-galactosidases (ABG) VejABG and VejGH117. Therefore, by experimentally verifying agarolytic enzymatic activity and transport of NeoDP4 into EJY3 cells, we revealed that EJY3 possesses both the known pathway and the newly discovered alternative pathway that involves α-NAOS hydrolase and ABG. IMPORTANCE Agarose is the main polysaccharide of red macroalgae and is composed of galactose and 3,6-anhydro-l-galactose. Many marine bacteria possess enzymes capable of depolymerizing agarose into oligomers and then depolymerizing the oligomers into monomers. Here, we experimentally verified that both a well-known agarolytic pathway and a novel agarolytic pathway exist in a marine bacterium, Vibrio sp. strain EJY3. In agarolytic pathways, agarose is depolymerized mainly into 4-sugar-unit oligomers by extracellular enzymes, which are then transported into cells. The imported oligomers are intracellularly depolymerized into galactose and 3,6-anhydro-l-galactose by two different agarolytic pathways, using different combinations of intracellular enzymes. These results elucidate the depolymerization routes of red macroalgal biomass in the ocean by marine bacteria and provide clues for developing industrial processes for efficiently producing sugars from red macroalgae.

Role of fatty acid oxidation in mechanism of action of gastric secretagogues

1980 ◽  
Vol 238 (3) ◽  
pp. G255-G262
Author(s):  
J. Chacin ◽  
G. Martinez ◽  
E. Severin
Keyword(s):  
Fatty Acid ◽  
Gastric Mucosa ◽  
Acid Secretion ◽  
Fatty Acid Oxidation ◽  
Acid Oxidation ◽  
Primary Role ◽  
Dependent Manner ◽  
Beta Oxidation

The role of beta-oxidation in the mechanism of stimulation of acid secretion was examined in toad gastric mucosa in vitro. The incubation with 4-pentenoate selectively inhibited in a dose-dependent manner the rate of 14CO2 formation from [1-14C]octanoate. Pretreatment with 20 mM 4-pentenoate sharply reduced the respiratory and secretory responses to theophylline and histamine. Tracer studies showed a major utilization of exogenous octanoate over glucose and pyruvate by the in vitro toad gastric mucosa. Theophylline and histamine stimulated by 69% the rate of octanoate oxidation. Over 60% of the increments in oxygen uptake produced by theophylline and histamine accounted for the increments in octanoate oxidation, whereas glucose and pyruvate together accounted for less than 25%. Octanoate-dependent respiration was shown to correlate with octanoate oxidation under both inhibition with 4-pentenoate and stimulation with theophylline. Theophylline stimulated by 25% the rate of octanoate oxidation in Cl--free glucuronate-nutrient solutions. The present work provides further evidence for the primary role of fatty acid oxidation in the mechanism of acid secretion in amphibian.

Generation of synthetic RNA-based thermosensors

2008 ◽  
Vol 389 (10) ◽  
Author(s):  
Torsten Waldminghaus ◽  
Jens Kortmann ◽  
Stefan Gesing ◽  
Franz Narberhaus
Keyword(s):  
Conformational Changes ◽  
Translational Control ◽  
Rational Design ◽  
Dependent Manner ◽  
Temperature Dependent ◽  
Structure Probing ◽  
Bacterial Rna ◽  
Computer Based ◽  
Shine Dalgarno Sequence

AbstractStructured RNAs with fundamental sensory and regulatory potential have been discovered in all kingdoms of life. Bacterial RNA thermometers are located in the 5′-untranslated region of certain heat shock and virulence genes. They regulate translation by masking the Shine-Dalgarno sequence in a temperature-dependent manner. To engineer RNA-based thermosensors, we used a combination of computer-based rational design andin vivoscreening. After only two rounds of selection, several RNA thermometers that are at least as efficient as natural thermometers were obtained. Structure probing experiments revealed temperature-dependent conformational changes in these translational control elements. Our study demonstrates that temperature-controlled RNA elements can be designed by a simple combined computational and experimental approach.

scholarly journals Nucleotide-dependent protein folding in the type II chaperonin from the mesophilic archaeon Methanococcus maripaludis

2003 ◽  
Vol 371 (3) ◽  
pp. 669-673 ◽  
Author(s):  
Andrew R. KUSMIERCZYK ◽  
Jörg MARTIN
Keyword(s):  
Atp Hydrolysis ◽  
Citrate Synthase ◽  
Single Gene ◽  
High Yield ◽  
Dependent Manner ◽  
Guanidinium Chloride ◽  
Methanococcus Maripaludis ◽  
Physiological Conditions ◽  
Dependent Protein

We report the characterization of the first chaperonin (Mm-cpn) from a mesophilic archaeon, Methanococcus maripaludis. The single gene was cloned from genomic DNA and expressed in Escherichia coli to produce a recombinant protein of 543 amino acids. In contrast with other known archaeal chaperonins, Mm-cpn is fully functional in all respects under physiological conditions of 37 °C. The complex has Mg2+-dependent ATPase activity and can prevent the aggregation of citrate synthase. It promotes a high-yield refolding of guanidinium-chloride-denatured rhodanese in a nucleotide-dependent manner. ATP binding is sufficient to effect folding, but ATP hydrolysis is not essential.

scholarly journals Borrelia burgdorferi Infection-Associated Surface Proteins ErpP, ErpA, and ErpC Bind Human Plasminogen

2008 ◽  
Vol 77 (1) ◽  
pp. 300-306 ◽  
Author(s):  
Catherine A. Brissette ◽  
Katrin Haupt ◽  
Diana Barthel ◽  
Anne E. Cooley ◽  
Amy Bowman ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Critical Role ◽  
Aminocaproic Acid ◽  
Factor H ◽  
Surface Proteins ◽  
Primary Role ◽  
Dependent Manner ◽  
Lysine Residues ◽  
Complement Regulator ◽  
Mammalian Infection

ABSTRACT Host-derived plasmin plays a critical role in mammalian infection by Borrelia burgdorferi. The Lyme disease spirochete expresses several plasminogen-binding proteins. Bound plasminogen is converted to the serine protease plasmin and thereby may facilitate the bacterium's dissemination throughout the host by degrading extracellular matrix. In this work, we demonstrate plasminogen binding by three highly similar borrelial outer surface proteins, ErpP, ErpA, and ErpC, all of which are expressed during mammalian infection. Extensive characterization of ErpP demonstrated that this protein bound in a dose-dependent manner to lysine binding site I of plasminogen. Removal of three lysine residues from the carboxy terminus of ErpP significantly reduced binding of plasminogen, and the presence of a lysine analog, ε-aminocaproic acid, inhibited the ErpP-plasminogen interaction, thus strongly pointing to a primary role for lysine residues in plasminogen binding. Ionic interactions are not required in ErpP binding of plasminogen, as addition of excess NaCl or the polyanion heparin did not have any significant effect on binding. Plasminogen bound to ErpP could be converted to the active enzyme, plasmin. The three plasminogen-binding Erp proteins can also bind the host complement regulator factor H. Plasminogen and factor H bound simultaneously and did not compete for binding to ErpP, indicating separate binding sites for both host ligands and the ability of the borrelial surface proteins to bind both host proteins.

scholarly journals Characterization of Tambjamines Pigment from Marine Bacterium Pseudoalteromonas sp. PM2 Indigenous from Alor Island, Indonesia

2021 ◽  
Vol 3 (1) ◽  
pp. 16-23
Author(s):  
Edi Setiyono ◽  
Marcelinus Alfasisurya Setya Adhiwibawa ◽  
Matheus Randy Prabowo ◽  
Tatas H.P. Brotosudarmo
Keyword(s):  
16S Rrna ◽  
Marine Bacteria ◽  
Marine Bacterium ◽  
Rrna Gene ◽  
Accession Number ◽  
16S Rrna Gene Sequences ◽  
Different Types ◽  
New Finding ◽  
Yellow Pigments

Pigments from marine bacteria have attracted the attention for scientists because of their extensive applications and currently exploration of new pigment sources from marine bacteria is still ongoing. Recently, we have successfully isolated six new yellow-pigmented marine bacteria, strain PS2, PM2, SB11, SB13, SB21, and SB23, isolated from seawater from different sampling sites on Alor Island, Indonesia. The UV−Vis and FTIR spectra of the crude pigment extracts of the six strains showed the characteristics of tambjamines, a group of yellow pigments commonly found in nudibranchs and bryozoans. Moreover, separation and characterization of crude tambjamines extract resulted in five different types of tambjamine with maximum absorbance at the wavelength of 374−392 nm. Based on the analysis of 16S rRNA gene sequences, strain PM2 was closely related to several species in genus Pseudoalteromonas with a similarity of more than 99%. Strain PM2 was designed as Pseudoalteromonas sp. PM2 with accession number LC505058. So far, only two marine bacteria have been known to produce tambjamine and they are from genus Pseudoalteromonas. Our new finding indicated that in the group of marine bacteria, tambjamine might be only synthesized by members from genus Pseudoalteromonas. 

scholarly journals Membrane voltage-dependent activation mechanism of the bacterial flagellar protein export apparatus

2021 ◽  
Vol 118 (22) ◽  
pp. e2026587118
Author(s):  
Tohru Minamino ◽  
Yusuke V. Morimoto ◽  
Miki Kinoshita ◽  
Keiichi Namba
Keyword(s):  
Ion Channel ◽  
Protein Transport ◽  
Atp Hydrolysis ◽  
Protein Export ◽  
Membrane Voltage ◽  
Activation Mechanism ◽  
Dependent Manner ◽  
Concentration Difference ◽  
Flagellar Protein ◽  
External Ph

The proton motive force (PMF) consists of the electric potential difference (Δψ), which is measured as membrane voltage, and the proton concentration difference (ΔpH) across the cytoplasmic membrane. The flagellar protein export machinery is composed of a PMF-driven transmembrane export gate complex and a cytoplasmic ATPase ring complex consisting of FliH, FliI, and FliJ. ATP hydrolysis by the FliI ATPase activates the export gate complex to become an active protein transporter utilizing Δψ to drive proton-coupled protein export. An interaction between FliJ and a transmembrane ion channel protein, FlhA, is a critical step for Δψ-driven protein export. To clarify how Δψ is utilized for flagellar protein export, we analyzed the export properties of the export gate complex in the absence of FliH and FliI. The protein transport activity of the export gate complex was very low at external pH 7.0 but increased significantly with an increase in Δψ by an upward shift of external pH from 7.0 to 8.5. This observation suggests that the export gate complex is equipped with a voltage-gated mechanism. An increase in the cytoplasmic level of FliJ and a gain-of-function mutation in FlhA significantly reduced the Δψ dependency of flagellar protein export by the export gate complex. However, deletion of FliJ decreased Δψ-dependent protein export significantly. We propose that Δψ is required for efficient interaction between FliJ and FlhA to open the FlhA ion channel to conduct protons to drive flagellar protein export in a Δψ-dependent manner.

Guaico Culex virus NSP2 has RNA helicase and chaperoning activities

2021 ◽  
Vol 102 (4) ◽  
Author(s):  
Xue-Yi Zhang ◽  
Ting Shu ◽  
Xiaotong Wang ◽  
Jiuyue Xu ◽  
Yang Qiu ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Rna Helicase ◽  
Life Cycles ◽  
Dependent Manner ◽  
Structural Protein ◽  
Rna Helicases ◽  
Genomic Rnas ◽  
Positive Sense ◽  
Group A ◽  
Strand Annealing

RNA-remodelling proteins, including RNA helicases and chaperones, function to remodel structured RNAs and/or RNA–protein interactions and play indispensable roles in viral life cycles. Guaico Culex virus (GCXV) is the first uncovered animal-infected multicomponent virus with segmented positive-sense genomic RNAs. GCXV belongs to the Jingmenvirus group, a diverse clade of segmented viruses that are related to the prototypically unsegmented Flavivirus. However, little is known about the exact functions of the GCXV-encoded proteins. Here, we show that the putative non-structural protein (NSP) 2 on segment 2 of GCXV functions as an RNA helicase that unwinds RNA helix bidirectionally in an adenosine triphosphate (ATP)-dependent manner, and an RNA chaperone that remodels structured RNAs and facilitates RNA strand annealing independently of ATP. Together, our findings are the first demonstration of RNA-remodelling activity encoded by Jingmenvirus and highlight the functional significance of NSP2 in the GCXV life cycle.

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